Smart, now a 21-year-old college student, gave her horrifying account in federal court as part of a proceeding over whether Mitchell is mentally competent to stand trial.
The 55-year-old, one-time street preacher has been behind bars since 2003 - mostly in a state mental hospital - but has yet to stand trial. Twice he has been ruled mentally incompetent in state court, and he has often demonstrated bizarre behavior, including incessantly singing hymns in the courtroom and once yelling at a judge to repent.
Smart testified that within hours of her 2002 kidnapping at knifepoint, she was led away to a secluded mountain campsite and in a quickie ceremony became the polygamous "wife" of the older man.
"After that he proceeded to rape me," Smart said, sharing for the first time publicly her account of the ordeal.
She said Mitchell showed her pornography and plied her with alcohol and drugs to lower her resistance to his sexual advances. Once, Smart said, she tried to fight Mitchell off by biting him. On the stand for nearly two hours, Smart was poised, her voice never wavering. She did not come face-to-face with her alleged tormenter. Mitchell was removed from the courtroom for disruptive behavior - singing hymns - before Smart arrived, and watched the proceedings from a holding cell.
A federal judge ruled earlier this week that Smart's testimony is relevant to the question of Mitchell's competency. Mitchell's competency hearing is not set to begin until Nov. 30, but Smart testified early because she is going on a religious mission for the Mormon church in Paris.
Smart's parents and other family members were in the courtroom to support her. Her father Ed Smart had already heard much of the story but said later outside court he had learned a few new details. He did not elaborate.
"She actually wanted to face him," Ed Smart said. "She asked if he could be muzzled and sit and watch."
He praised his daughter's composure.
"I was absolutely amazed at her strength," he said, his eyes teary. "I don't know how she could have done a better job than she did."
Smart was 14 when she was abducted from her bedroom in the middle of the night. In a surprising turn that transfixed the country, she was rescued in March 2003 after a motorist spotted her walking the streets of a Salt Lake City suburb with Mitchell and his wife, Wanda Eileen Barzee.
Smart testified that in the days immediately following the kidnapping, Mitchell held her captive with the help of a 10-foot cable bolted to her leg and tethered to a line stretched between two trees. She said Mitchell threatened to kill her if she yelled or tried to get away.
Smart said Mitchell would rape her three to four times a day. There was some respite - usually when Barzee became upset over Mitchell's relationship with Smart - but it never lasted, Smart said.
Mitchell is charged in state court with kidnapping and sexual assault. Last year, he was indicted on federal charges of kidnapping and transporting a minor across state lines. In both the state and federal cases, experts have split over Mitchell's competency.
Mitchell's lawyers maintain he is incompetent and suggested that evidence of his delusions can be found in his religious rambling and writings, including a 27-page manifesto he called "The Book of Emmanuel David Isaiah."
Smart said he read from the book repeatedly during her captivity, often sang hymns and laced his conversations with religious language. Throughout her captivity, Smart was forced to wear a white, ankle-length robe, a head scarf and two veils across her face.
"He told me he was a prophet," Smart said under cross-examination by Mitchell's lawyer. "He said he was the voice of God on Earth and that he would reign over God's children until Jesus came."
But she also said his religious revelations seemed to come only when he wanted something, or when he was trying to calm Barzee. Smart said she believed Mitchell always knew that he could be punished for her kidnapping and understood how the court system worked.
She said he gave her an alias - Augustine Marshall - and told her what to say to police if they were ever questioned. He also bragged about skirting previous accusations of sexual abuse and fooling others, Smart said.
Never in nine months did Mitchell appear confused or out of control, Smart testified: "He was a very capable, intelligent human being."